Taxonomic revision of the Canthidium Erichson, 1847 species of the gigas group (Coleoptera, Scarabaeidae, Scarabaeinae)

The gigas species group of the subgenus Canthidium (Neocanthidium) is defined and described. This species group is composed of three described species [C. gigas Balthasar, 1939, Brazilian Atlantic Forest, including intrusions into Cerrado, C. bokermanni (Martínez et al., 1964), Chaco and western Cerrado in Brazil, Bolivia, Paraguay, and Argentina, and C. kelleri (Martínez et al., 1964), Brazilian Cerrado and neighbouring open areas] and three new species: Canthidium stofeli sp. nov. from the western and southern regions of the Brazilian Amazon, Canthidium feeri sp. nov. from French Guiana, and Canthidium ayri sp. nov. from the Brazilian Atlantic Forest. We present descriptions and redescriptions, illustrations, an identification key and comments on the distributions of the species of the gigas group.